In steam generating systems, such as boilers, the condensate feedwater may contain a variety of contaminants which will contribute to inefficiencies in the operation of the system. Under steam generating conditions, some compounds will detrimentally affect the heat transfer characteristics of the entire system. This results in undesirable downtime to make costly repairs.
Acids are especially corrosive. They may be generated from a number of precursors which are present in the feedwater introduced into the system. Under the elevated temperature conditions necessary to generate steam, these precursors will become acidified. Sugars, such as glucose and fructose, are such precursors. When these sugars are oxidized, they will form various organic acids. These acids, then, will be available to corrosively attack the internal metallic surfaces of the entire steam generating system.
It is most desirable, therefore, to eliminate or neutralize the acidic species in the condensate feedwater. It is even more desirable, however, to eliminate the precursor from the feedwater before it turns acidic. In order to do this, the presence of the precursor must first be detected.
In condensate feedwater which may contain carbohydrates, it is very important to be able to detect the presence of these "sugars" as soon as they enter the feedwater train and at the lowest concentration possible. Conventional analysis methods for detecting the presence of sugars in aqueous systems include the use of Fehlings solution, Benedicts solution (copper is reduced by the sugars present) or by glucose enzymatic test strips (available from Lilly as TES-TAPE.RTM.). Unfortunately, these methods are limited in their detection limits. For example, enzyme test strips fall to successfully detect the presence of sugars at concentrations of lower than 0.05% or 500 ppm. The high concentration detection minimum limit renders such methods useless where sugar concentrations are below this value but still high enough to generate corrosion causing acids.
Additionally, the use of test methods such as Benedicts or Fehlings, requires that the solution be heated to boiling. The temperature limitation mitigates against the use of such methods to analyze higher temperature condensate streams. Furthermore, these tests are not quantitative and render photometric analysis ineffectual because of the precipitate that forms. It is an object of the present invention to provide a method for quantitatively detecting the presence of sugars in steam generating system feedwaters at very low concentrations. It is a further object to provide a method for detecting the presence of low concentrations of sugars in high temperature condensate streams on an on-line basis.